Hydraulic cylinder and piston.



L KENNEDY.

VHYIJRAULIC CYLINDER AND PISTON.

MPLICATION FILED FEB. 2.ll8.

J. KENNEDY HYDRAULIC CYLINDER AND PlsToN.

APPLICATION FILED FEB. 23 I'BIB.

Patented Feb. 25, v1919.

2' SHEETS-SHET 2 WITN ESSES JULIAN KENNEDY, F PITTSBURGH, PENNSYLVANIA.

HYDRAULIC CYLINDER'AND ris'ron.

clear, and exact description, reference being had to the accompanying drawings, formlng part of this specification, in which-- Figures l, 2 and 3 are longitudinal sectional views showing'two different forms of my invention as applied to hydraulic cyl-\ inders; and

Fig. 4 is a sectional elevation showing the invention applied to a piston or plunger.

My invention has relation to hydraulic.

cylinders and pistons, and is particularly applicable to cylinders and pistons where relatively high working pressures are employed. Such cylinders usually have an internal lining in the form of a bronze bushing which forms the immediate bearing for the piston or plunger; andit is also common to provide the pistons or plungers with a similar bushing forming the wearing surface thereof.

. In practice, it is diiiicult to obtain bushings of this character which are sufficiently free from porosities or other defects to prevent some of the working fluid from being forced through them under the working pressures employed in the cylinders. When such leakage occurs, even in relatively small volume, it freqluently happens that the pressure in the cy inder forces the leakage liquid around the piston' between the outer surface of the bushing and the inner'wall of the cylinder proper. VThis is likely to cause the bushing to 'buckle or collapse inwardly in front of the piston in the manner indicated at a in Fig. l, thereby destroying the bushingand perhaps causing serious results in the apparatus with which the cylinder is used. A similar result may follow from a defective piston bushing.

My invention is designed to provide means of simple and eective character. for overcoming the effect of such leakage to thereby prevent buckling or collapsing of the cylinder or piston bushing; and it consists broadly in providing leakage release passages or channels intermediate the bushing and the body of the cylinder or piston proper and which are arranged to intercept any leakage which may occur through the bushing.

Specification of Letters Patent.

Patented Feb. 25, 1919.

Application led February 23, 1918. Serial No. 218,625.

Referring first to that form of myvinvent1on shown in Fig. 1, the numeral 2 designates a hydraulic cylinder of any usual char- .acter having the lining bushing 3. 4 desig.

nates the piston or plunger also of any usual character.

In the specific form. of my invention l shown in this fi re, I rovide the outer surface of the bus ing w1th a continuous helical shallow groove 5, extending throughout the major portion of the length of the bushing and running clear to the flanged end 6v thereof. At this end, said groove communi- -cates with the leakage space -7, whichv is formed between said flange and the adjacent wall of the cylinder,` and this space, in turn,

is shown as communicating with a leakage l opening 8 between the-cylinder flange and the head 9. v

Any Aleakage which may occur through 'the wall of the bushing will'be intercepted fby 'some portion of the helical groove before the liquid has traveled any considerable di'stance, and under the pressureinthe cyl- "inder, such liquid will ultimately find its way to the leakage escape openings at the end..

If desired, however, the wall of the cylinder may be provided at intervals with small escape openings 10,' as shown in Fig. 2. Very small openings of this character will be sufficient and may, in some cases, be used without the relief passages between the cylinder wall and bushing. 1

I do noft limit myself rto the use of a helical groove in the bushing, as the means for intercepting the leakage, since the leakageintercepting passages or channels may be of various forms and arrangement. They may also be formed in the inner4 wall of the cylinder, as shown at in Fig. 3, but it is usually more convenient to form them lin the i i `bushing prior to its insertion into .the cylinder. i'

In Fig. 4, I have shown my invention applied to a piston or plunger. In this figure., 11 designates |a cylinder and 12 its piston or plunger, these 'parts' being shown by way of example, as used for actuating a die or press member 13.. 14 designates the bushing' and 15 is the helical groove which may be formed either in the external surface of the piston body, as shown, or in the inner surface of the bushing, the essential thing being that it shall be between the parts in posi- My invention not only overcomes the difculties hereinbefore referred to, and prevents buckling and collapse of cylinder and piston bushings, but it also enables the use of a thinner bushing than has heretofore been required, 'a thicker bushing having heretofore been necessary in an attempt to prevent leakage.

My invention also results in a considerable saving in the manufacture of the bushings, since heretofore it has frequently been necessary to discard a large percentage of the finished bushings, owing to the fact that they were sufficiently defective to permit leakage and I claim: 1. A hydraulic cylinder or piston comprising a -body and a bushing, said body and bushing having -a leakage-intercepting passage or c'hannel between them, substantially as described.

2. A hydraulic cylinder or piston having I a body and a bushing, said body and bushing having a leakage-inftercepting passage or channel between them, said passage or channel having a discharge connection leading to the exterior of the cylinder, substantially as described.

3. hydraulic cylinder having an inte-"l rior ll'nmg or bushing, said parts having a.

could not, therefore, be used.

leakage-interceptingpassage or channel between them, and the wall of the cylinder rior lining or bushing, the latter having its' external surface provided with a helical leakage-intercepting groove, substantially as described. A

5. A hydraulic cylinder having an interior lining or bushing, the latter having its external surface provided with a helical leakage-intercepfting groove, and the wall of the cylinder having a plurality of escape openings therethrough, substantially as described.

y 6. A bushing or lining for hydraulic cylinders, said bushing having its outer surface provided with a helical ,leakageintercepting groove, substantially as described.

7. A hydraulic cylinder having an interior lining or bushing and the wall of the cylinder having therein a plurality of small leakage openings leadingfrom the outer surface of the bushing, substantially as described.

In testimony whereof, I have hereunto set my hand.'

JULIAN KENNEDY. 

